Interlocking system



Feb. ze, 1985.

A+ non TOACLOAD INVENTOR Jos Patented Feb. 26, 1935 UNITED sTATEs PATENT oFFlcE a 1,9,2'17 m'rEaLooxmG SYSTEM Application March 13, 1934, Serial No. 715,373 12 Clllml. (Cl. 171-97) This invention relates to safety devices, and more particularly to an interlocking system suitable for electric, hydro-electric, or hydraulic equipment. I

In the preferred embodiment illustrated in the accompanying drawing and explained in detali in the following description, the 'invention' is shown as it may be applied to the control of electrical circuits and parts such as are employed on aircraft to energize radio and other apparatus carried by the craft; and although certain of the appended claims are directed to the resultins method or means of control of an aircraft power supply system, itis to be understood that the invention, in -a broader aspect, embraces the disclosed novel interlocking means as applied to this particular use or to any'of those other uses (such as the control of high potential oil switches or valves in industrial and commercial power plants of either an electric, hydro-electrlc or hydraulic character) which will readily suggest themselves to skilled persons who examine the present disclosure.

In providing radio transmitting apparatus for use in airplanes, it is not only desirable that the weight of the apparatus be maintained at a minimum, but it is further desirable that means, independent of the airplane engine, be provided for actuating the transmitting apparatus in order that signals may be sent or the equipment tested when said engine is not in operation. To supply this need there have been employed theretofore multiple output generators adapted to be driven mechanically from the engine of the plane when the latter is in operation and also adapted for electrical energization independent of the engine when the latter is not running. T he present invention contemplates such independent electrical energization from a source of energy which may'be located outside the craft itself and which may be utilized to energize the generator through passage of current to the same parts thereof as have been used to energize the unit electrically heretofore, the arrang'ement'being such that this external energization, when employed, automatically necessitates the previous de-energization ot the entire dynamo electric machine and also necessitates an opening of at least one of the cincuits normally supplied by the generator when being mechanically driven. This automatic action is due to the novel interlocking means above refen'ed to, and the said interlocking means further acts'to prevent a closing of the last-named out-put circuit so long as the machine is being electrically energized fromV the extemal source.

For the purpose of eliminating the hazards associated with the use of high tension current,l w

various devices have been employed, such as electricalLv operated interlocks. In one of these interlocks, a relay is employed to open and close one of the switches, the relay circuit being controlled by a key-manipulated switch, withdrawal of the key from the switch serving to de-energire the relay circuit. When the key is withdrawn from the switch, it may be used to unlock another switch or a cabinet containing other switches.

It is an object of the present invention to provide a mechanically operated interlock for such switches, whereby certain hazards and disadvantages will be eliminated and proper sequence of operation will be assured, without the need of any key whatever.

These and other objects reside in the specific construction, inter-relation and application of the component parts entering .'nto an embodiment of the invention and will appear more fully in thedetailed description of the preferred embodiment which follows:

In the drawing:

Fi'g. 1 shows schematically the electrical circuits, switches and switch Operating means involved when the invention is applied to the control of a combined direct and altemating current generator, or "altemator" as it is more commonly. called; and

Figs. 2 and 3 show the switches and switch operating means at successive stages in the opera- .tion of starting ("exciting") the generator, or

Operating it as a motor-generator (dynamotor).

Referring to the drawing, reference character 4 designates the main ileld winding and reference characters 5 and 6 the commutator and direct current exciting field windings, respectively, of an alternating current generator adapted to bev normally driven through mechanical connections 3 constituting part of the power plant (internal combustion engine usually) of the craft. This commutator 5, together with collector rings 7, normally feed the lights, radio tubes, etc. which, in conjunction with battery 8, completeV the electrical equipment carried by the craft. 'A second battery 10, or other external source. is shown as the means for initially exciting the machine, also for energlzing commutator 5 to run the machine as a dynamotor.

It is necessary, as will be appreciated by those iamiliax' with the operation 'of dynamo electric machinery. to guard against an untimely or otherwise improper manipulation of the switches controlling the flow of current in any of the various windlngs of the machine, for the closure of one of these switches in improper sequence, may result in serious injury to the machine, the associated equipment, or the operator. Speciiically, in a hook-up of the character shownj in Fig. 1, it would be quite undesirable to permit the battery 10 to remain in circuit with any part of the generator after the latter has been fully excited and the mechanical driving means 3 begins to deliver torque. The present invention prevents such an occurrence by mechanically interlocking the controlling switches, one of which is shown as constituted by a pair of contact ilngers 13 and 14 extending from a portable plug 11 receivlng conductors 15 and 16 leading to the terminala of battery 10. Another switch is shown in the form of a current conducting brush 12 insertible between switch blades 19 and 20 to connect the generator with the load.

As shown, the brush 12 is mounted in and suitably insulated from the cylindrical end portion of an arm 22 extending from a sleeve 23 freely mounted on a shaft 24 at one end of which there is an Operating handle 25 and at the opposite end of which there is a second arm 26 preferably integral with the shaft 24 and similar to arm 22 in that it carries at its outer end a brush 27 adapted to span a pair of current conducting switch plates 28 and 29, the former being connected by a conductor 31 to the positive terminal A plus of the commutator 5 while the other switch plate 29 connects with a contact post 32 from which conductors 33 and 34 proceed to elements 36 and 37 respectively. The element 36 is a contact socket mounted in a fixed plug 38 of suitable insulating material and in position to rcfrister with the contact pin 13 previously described.

In order to prevent premature registry of the pin 13 with the socket 36, and also to prevent premature registry of the pin 14 with a second socket 39 in the plug 38, a member 43 is provided which blocks the entry of the pins 13 and 14 into the sockets 36 and 39 except when the switches 12 and 27 are in predetermined positions. As shown, the member 43 is integral with the sleeve 23 and extends radially therefrom at a position approximately 180 degrees from the radial position of the arm 22 and thereby occupies a position as shown in Fig. 1 when the switches 12 and 27 are closed. In this position the plugs 11 and 38 (the latter beingdixed in relation to arm 43) cannot be brought into registry.

In order to produce simultaneous opening movements of both the switches 12 and 27 in response to swinging the handle 25 in a counterclockwise direction, the arm 26 is provided with a finger 42 extending therefrom in such a position that it normally contacts with the edge of the arm 22 and therefore causes a movement of the said arm to the position indicated in Fig. 2 upon a corresponding movement of the handle 25 and switch arm 26. As shown, this movement is sufficent to swing the hlocking arm 43 out of the path of the plug 11 and therefore permit closure of the switches constituted by the contacts 13, 14, 36 and 39. When this operation is performed, current is caused to flow from the battery 10 through conductor 15 and switch contacts 13 and 36 to the conductors 33 and 34 and thence,

through the adjustable rheostat 37 to the field winding 6 of the machine, thus providing the initial excitation thereof. the return clrcuit being by way of the conductors 44-45 contacts 39 and 14 and conductor 16. It will be noted that prior to such excitation the switches 12 and 27 have been opened and therefore the machine is protected against iniury which would otherwise result from a premature closure of these switches.

One end of a torsion spring 49 presses upon a pin 51 projecting from the side of the switch arm 22, and the other end bears against an abutment 52 secured to the housing, not shown. It will be evident therefore, that the spring 49 normally tends to return the switch arm 22 from the position shown in Fig. 2 and Fig. 3 to the position shown in Fig. 1, but as shown in both Figs. 2 and 3 such return is prevented by the blocking action of the plug 11, due to its being in the path of the arm 43.

It is also desirable to provide a sequence as between the switches 27 and 12 whereby the former is closed while the closu're of the latter is delayed pending a reopening of the battery circuit Controlled by the switch members 13 and 14. In the form shown, such sequence is assured so long as the switch plug 11 remains engaged with the plug 38 and thus blocks any clockwise motion whatever of the arm 43 with which the switch arm 22 is integral, as above explained. Therelore. the return swing of the handle 25 from the position shown in Fig. 2 to the position shown in Fig. 3 (corresponding to the initial position of Fig. 1) has no effect whatever upon the switch arm 22, but lt is effective to reclose the switch 27 mounted on the switch arm 26 and thereby cause current fiow through the armature winding 5, the circuit passing from the battery 10 by way of conductors 15, 13, 36, 33, 29, 27, 28 and 31 and returning to the battery by way of conductors 44, 45, 39, 14 and 16.

After the initial energization of the wlnding 6 has been effected in the manner above, described. and operation of the machine as a dynamotor is no longer desired, the switch 12 may then be closed to throw the load upon the machineprovided, however, that the battery 19 is first disconnected by separation of the switch plugs 11 and 38. Accordingly, the procedure is first to withdraw the plug 11, whereupon it becomes possible for the spring 49 to snap the switch arm 22 back to the position indicated at Fig. 1, the integrally formed arm 43 at the same time returning to the position indicated at Fig. 1 and thereby blocking a re-insertion of the switch plug 11 so long as the load remains connected to the machine. If desired, a reverse current relay may be inserted inh the positive side of the line 62 in the position indicated at 63, namely between the switch 12 and the battery connection 64, in cases where such a connection 64 and a corresponding connection 65 are provided in order` that the load 66 may be supplied directly by the plane's battery 8 on certain occasions.

Although only one embodlment is iliustrated in the accompanying drawing, it is to be expressly understood that this drawing is for the purpose of illustration only and is not to be construed .as a deflnition rof the limits of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. The combination with a dynamo electric machine of a circut energizable therefrom and mechanical driving means therefor, means distinct from said mechanical driving means for energizing said machine, said last named means including an external source of current, and a switch in each of said circuits, and interlocking means preventing closure of one of said switches except when the other is in a predetermined position, said last named means including a pair of blocking elements movable into mutually blocking positions, and means acting in response to withdrawal of one of said blocking elements for causing the other of said blocking elements to move into blocking relation to the first named biockingl element.

3. The combination with a dynamo electric machine of a circuit energizable therefrom and mechanical driving means therefor, means distinct from said mechanical driving means for energizing said machine, said last named means including an external source of current, and a circuit from said source to said machine, a switch in each of said circuits, and interlocking means preventing closure of one of said switches except when the other is in a predetermined position, said last named means including a cylinder constituting a part of one of said switches, an arm normally preventing movement of 'said cylinder to switch closing position, and means for simultaneously withdrawing said arm and opening the other of said switches.

4. The combination with a dynamg electric machine of a circuit energizable therefrom and mechanical driving means therefor, means distinct from said mechanical driving means for energizing said machine, said last named means including an external source of current, and a circuit from said source to said machine, a switch in each of said circuits, and interlocking means prevnting closure of one of said switches except when the other is in a predetermined psition, said last named means including a cylinder constituting a' part of one of said switches, an arm normally preventing' movement of said cylinder to switch closing position, and means for simultaneously withdrawing said arm and opening lthe other of said switches, and means for preventing a -closing of said last named switch, said last ed means being constituted by said cylinder.

5. The combination with a dynamo electric machine of a circuit energizable therefrom and mechanical drivingmeans therefor, means distinct from said mechanical driving means for energizing said machine, said last named means including an extemal source of current, and a :ircuit from said source to said machne, a switch in .each of said circuits, and interlocking means preventing closure of one of said switches except when the other is in'a predetermined position, said last named means including a .plug constituting a part of one of said switches, an arm normally preventing movementof said plug to switch closin'gr position, and means for sfmulvtaneously withdrawing said arm and opening the other of said` switches.

'machine of a circuit energizable therefi'om and mechanical drlving means therefor, means disswitch in each of said circuits, and interlocking means preventing closure of one of said switches except when the other is in a predetermined position, said last named means including a plug constituting a part of' one of said switches, an arm normally preventing movement of said plug to switch closing position, means for simultaneously withdrawing said arm and opening the other of said switches, and means for preventing a re-closing of said last named switch. said last named means being constituted by said plug.

'1. The combination with a dynamo electric machine of a circuit energizable therefrom, means for energizing said machine, said last named means including an external source of current, and a circuit from said source to said machine, a switch in each of said circuits, and interlocking means preventing closure of one of said switches except when the other is in a predetermined position.

8. The combination'with a dynamo electric machine of a circuit energizable therefrom, means for energizing said machine, said last named means including an extemal source `of current and a circuit from said source to said machine, a switch in each of said circuits, and interloclring means preventing closure of one of said switches except when the other is in a predetermined position, said last named means including a pair of blocking elements movable into mutually blocking positions, and means acting in response to withdrawal of one of said blocking elements for causing the other of said blocking elements to move into blocking relation to the first named blocking element.

9. The combination with a dynamdelctric machine of a circuit energizable therefrom, means for energizing said machine, said last named means including an external source of current, and a circuit from said source to said machine, a switch in each of said circuits, and interlocking means preventing closure of one of said switches except when the other isv in a predetermined position, said last named means including a cylinder constituting a part of one of said switches, an arm normally preventing movement of said cylinder to switch closing position, and means for sixnultaneously withdrawing said arm and opening 'the other of said switches.

10. The combination with a dynamo electric machine of a circuit energizable therefrom, means for energizing said machine, said last named means including an external source of current, and a circuit from said source to said machine, a switch in each of said circuits, and interlocking means proventing closure of one of said switches except'when the other is in' a predetermined position, said last named means including a cylinder constituting a part of one of said switches, an arm normally preventing movement of said cylinder to switch closing position, means for simultaneously withdrawing said arm and opening the other of said switches, and means for preventing a re-closing of said last named switch, said last named means being constituted by said cylinder. 6. The combination with a dynamo electric 11. The combination with a dynamo electric machine of a circuit energizable therefrom,

means for energizing said machine, saidclast named means including an external source of current, and a circuit from said source to said means including an external source of current. and a circuit from said source to said machine. a switch in each of said circuits, and interlocking means preventing closure of one of said switches except when the other is in a predetermined position, said last named means including a plug constitutinz a part of one of said switches. an arm normally preventinz movement of said plug to switch closing position, and means for simuitaneously withdrawing said arm and opening the other of said switches, and means for preventing a re-closing of said. last named switch. said last namedmeans being constituted by said plug. i

JOSEPH W. ALLEN. 

